Operational Excellence - Rotating Equipment

In process plants we typically have a significant investment in rotating equipment - pumps, compressors, fans, machine tools, and motors of every description. Synchronous principals always talk about maintenance as a reliability function rather than a repair function, so we are always interested in best practices for rotating equipment. To keep a rotating equipment reliability program manageable we recommend it include all equipment larger than 10 horsepower, unless a smaller motor is on your tier 1 critical equipment list. Best practices to base your reliability program include:

Vibration Standards:
- General Motors Specification V1.0-1993 sets maximum vibration standards for particular types of equipment at specific rotational frequencies.
- Hewlett Packard Application Note 243-1 "Effective Machinery Measurements Using Dynamic Signal Analyzers" specifies acceptable vibration levels for rotating equipment.
More references and materials are available from the Vibration Institute at www.vibinst.org .

Balancing Specifications:
- ISO DR1940 Grades 1.0, 2.5, 6.3, and 16 are the gold standards. Grade 6.3 is the industry standard; best practice for critical equipment is Grade 2.5; and Grade 6.3 is appropriate for non-critical equipment.

Resonance Standards:
- Motor manufacturers have reduced the mass of their equipment in an effort to reduce costs. This, of course, leads to an increase in resonance problems - especially in high efficiency motors. Best practice dictates that when purchasing a motor or other rotating equipment, the resonance frequency of any component or frame be at least 30% higher than the maximum attainable speed of the machine.

A solid reliability plan for rotating equipment should also consider specifications for bearing installation, machinery alignment, and motors. More on these subjects to come.

Synchronous LLC is committed to maintaining a continuing dialogue on operational excellence and best practices for the process manufacturing industry. To pose a question, contribute a best practice, or otherwise add to the dialogue, send a note to RobBaldwin@SynchronousLLC.com . To subscribe to our weekly newsletter send your preferred email contact address to Webmaster@SynchronousLLC.com with SUBSCRIBE in the subject line.